Effect of R-134a inundation on enhanced tube geometries
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Data showing the effect of refrigerant R-134a condensate inundation on the shell-side heat transfer coefficient are presented for four enhanced tube geometries. The test bundle consists of five instrumented tubes in a five-row test bundle surrounded by inactive tubes in a staggered tube arrangement with a horizontal pitch of 22.2 mm (0.875 in.) and a vertical pitch of 19.1 mm (0.75 in.). Simulations of the effect of inundation up to a depth of 30 rows are presented. The data were obtained at a saturation temperature of 35 °C (95 °F) at heat fluxes of approximately 27,000 and 55,000 W/m2 (8,560 and 17,400 Btu/[h·ft2]) on a 1,024-fpm (26-fpi) tube, a low-fin 1,475-fpm (40-fpi) tube, and two enhanced tubes, designated the Tu-Cii and the G-SC. The data show that the Tu-Cii enhanced geometry performs more than twice as well as the other geometries at low inundation levels. At high inundation rates with condensate Reynolds numbers above 2,000, the Tu-Cii performance falls to within 10% of the other geometries. The data also show that those tubes with continuous, screw-type fins show little effect due to condensate inundation, particularly at low condensate flow rates. Overall, the Tu-Cii performed the best, followed by the G-SC and the low-fin 40-fpi and 26-fpi geometries.
author list (cited authors)
Rewerts, L. E., Huber, J. B., & Pate, M. B.